Electric switch



ELECTRIC SWITCH Filed Oct. 30, 1926 bodying the invention.

Patented Mar. 3, 1931 UNITED STATES PATENT OFFICE TALMA T. GREENWOOD, OF EAST TEMPLETON, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL MANUFACTURING COBPOR A CORPORATION OF MASSACHUSETTS ATION, OF SOUTH BOSTON, MASSACHUSETTS,

ELECTRIC SWITCH Application filed October 30. 1926. Serial No. 145,329.

This invention relates to electric switches and particularly to switches adapted to control alternating current circuits and has for an object the provision of a switch ada ted 5 to interrupt its circuit with great rapi ity, and, in the case of an alternating current, to interrupt the circuit in not more than the time of one-half a cycle.

This invention utilizes that principle of alternating current rectification wherein a stream of cool fluid is passed along the length of an alternating current are at avelocity at least equal to the velocity of the ions of the are, so that current cannot pass between the 1 electrodes in a direction opposed to the fluid stream although current can pass in the gpiposite direction, with the result that one h of the alternating current wave is suppressed.

In the switch or circuit interrupter constructed to make use of this princi Is, current can pass between the separate switch members only in the direction of the fluid stream and is prevented from passing in the opposite direction. The are will thereby be extinguished at least at the end of a half wave.

It is also an object of this invention to provide two sets of circuit interrupting, or arebig, members connected electrically in series 39 and so arranged that fluid streams are directed in opposite direction with the respect to the instantaneous direction of How of current. Under these conditions current ma pass between one set of arcing members in the di- 35 rection of the fluid stream but is prevented from passage between the other set of separated members against the direction of move ment of the other stream. The circuit, therefore, is interru ted practically instantaneously or in less t llan one-half a c cle.

A further object of the invention isgenerally to improve the construction and operation of circuit interrupters.

Fig. l is a view of the electric switch em Fig. 2 is a more or less dia ammatic showing of the invention, the switch being shown in a section taken, through the stationary and movable switch mem 1 Fig. 3 is a. sectional detail of a set of switch members in separated condition and illustrating particularly the flow of the fluid stream between the members.

As here shown, the switch embodying this invention includes the stationary switch members comprising the conducting studs 10 and 12 which are insulated from a supporting frame 14 by insulators 16 of more or less usual construction. The conducting studs 10 and 12 are tubular or are provided with passages 18 therethrough. The lower ends of said studs may be formed with slots 20 therein as shown 1n Fi 3 or may be otherwise arranged to provi e yielding contact terminals 22. The movable switch member includes an insulating switch rod 24 which supports at its lower end a transversely disposed conducting bar 26. Movable contact members comprising upstanding rods 28 and 30 are secured to the ends of said bar 26 and are adapted to be moved into and out of the tubular contact terminals 22. The movable switch member may be raised and lowered by the element 32 of any suitable switch operating mechanism. The movable switch member can be held releasably in switch closed position by the pivoted latch 34 which is adapted to enter a slot 36 of the switch rod 24 and thereby hold the switch closed. The latch-may be removed from holding engagement, whereby to permit the switch to move to open circuit position by gravity or otherwise, by the electro-magnet or solenoid 37.

The stationary switch members are rovided with the usual line terminals 38 an 40.

The electro-magnet 37 is arranged to open the switch upon overload by means of a current transformer 42 energized from the circuit through the switch.

The passages 18 in said tubular studs 10 and 12 are ada ted to be in communication witha source 01 fluid and preferably an elastic fluid so that when the switch opens streams of the fluid can pass out of the studs into the arc zones in the irection of movement of the contact members 28 and 30. To this end a source of air under pressure as the storage tank 44 is provided. Means including an automatically operated air pump 46 may be provided to maintain a constant source 0 air under pressure in said tank. The upper ends of said studs are connected through insulating pipes 48 with a similar insulating pipe 50, which may be a rubber hose for examp e, and which is in communication with the pressure air in said tank 44. A valve 52 is introduced in said pipe 50 and serves to control the flow of air from said tank to the switch. Said valve is here shown as electrically operated by means of the electro-magnet 54 which is energized from the circuit of the switch through the current transformer 56. Said valve is adapted normally to be open when there is an appreciable amount of current in the switch circuit so that air under suitable pressure is always present in the stud passages in readiness to issue therefrom when the switch is opened. The passages 18 in said stud are normally closed by the movable contact members 28 and 30; and the pressure of air against said contacts serves to accelerate the switch opening movement.

With the construction above outlined, when the switch is opened, air is caused to flow out of the ends of the tubular studs and against and about the tips of the movable contact members 28 and 30 as illustrated in Fig 3.

he pressure of the air in the switch studs is adapted to be such as to impart to the air streams a velocity which is comparable with the velocity of movement of the current conductin ions of the arc, and preferably is somewhat greater than such velocity. Since the velocity of the ions is somewhere around twelve or thirteen hundred feet per second, the velocity of the air issuing from said studs should be of this o'rder o magnitude and preferably somewhat greater. This velocity can be easily obtained with an air ressure of around thirty pounds per square inch or upwards.

Considering only one set of separable switch members, as the stud 10 and the contact member 28, if the instantaneous flow of current is from the stud 10 to the contact member 28, the current flow and consequently the arc may persist for one-half a cycle. When the current reverses, however, the direction of movement of the conducting ions is against the direction of flow of air. Since the velocity of the air stream is greater than the velocity of the conducting ions no current canpass. Consequently, the circuit will be interruplted at the end of the half cycle.

While t e current ma pass in the direction of air fiow at one set 0 contacts, the direction of the current is against the air stream at the other set of contacts and the flow of current will be inhibited at these contacts. As a consequence, with the use of two sets of contacts, the circuit will be interrupted at least in something less than one-half a cycle.

Smceythe valve 52 is held 0 en by the presence of current in the switch circuit, when the circuit is interrupted and the current falls to zero, the valve 52 will close thereby shutting 0d the flow of air and prevent undue waste of air. When current is in the circuit, however, the valve will be open thereby to condition the switch for operation.

The cooperating contact members of each set, and the fluid stream, thus constitutes an electric rectifier or valve which permits current to flow in one direction only through it; and the two rectifiers or valves are connected in opposition, thus to prevent the flow of current in either direction.

The construction may be otherwise modified without departing from the spirit of the V invention.

I claim:

1. An electric switch having two sets of cooperating separable switch members which are connected in series and are arranged when in contact to complete the circuit through the switch, said sets of separable switch members constituting electrodes of rectifying devices characterized by one rectifying device opposing the flow of current passed through the other rectifying device, and means to separate the contacts of said sets whereby to initiate the rectifying action and to interrupt the circuit through the switch.

2. An electric switch having the combination of two sets of separable contact members connected electricall in series and means to direct streams of flui to move in opposite directions with respect to the path of current between said contact members and at a velocity which inhibits the flow of current in the arcs in a direction which is opposite to the direction of flow of the fluid streams and in the line of separation of said contact members.

3. An electric switch having the combination of two sets of se arable contact members connected electricall in series, and means to direct streams o fluid to move in opposite directions with respect to the path of current between said contact members and in the line of said contact members and with a velocity at least equal to the velocity of the conducting ions in the spaces between the separated contactmembers of the sets.

4. An electric switch having the combination of two sets of cooperating separable contacts electrically connected in series, and means to direct fluid streams in opposite directions with respect to the current flow between said contact members when separated and in the direction of normal arc conduction between said contact members and at a velocity of upwards of one thousand feet per rent flowing between the contact members of said sets and 1n the line of normal are conduction therebetween and at an initial prcssure of not less than approximately thirty pounds per square inch.

6. An electric switch constituting an electric valve, means to provide fluid streams to govern the valve action, and serially connected sets of cooperating separable contact members arranged in the zone of said fluid streams, said fluid streams arranged to be directed in opposite directions with respect to the current flowing between the sets of contact members whereby current passed between one set of contact members is always opposed by the valve action of the other set of contact members and the fluid stream as sociated therewith.

7. An electric switch having pressure fluid means biasing it to switch open condition and lacking means to hold the switch releasably in closed position against said fluid biasing means, said fluid means also constituting means operative upon opening-said switch to rectify the current conducting arc.

In testimony whereof, I have signed my name to this specification.

TALMA T. GREENWOOD.

CERTIFICATE OF CORRECTION.

Patent No. 1,794,682. Granted March 3, 1931, to

TALMA T. GREENWOOD.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, lines 100 to 103, claim 2. strike out the words "and at a velocity which inhibits the flow of current in the arcs in a direction which is opposite to the direction of flow of the fluid streams" and insert same to follow after the word members and before the period; page 3, line 21, claim 7, for "lacking" read locking; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 31st day of March, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

